-LRB- CNN -RRB- -- Jebb Graff is n't turned off -- yet -- by Carnival Cruise Lines ' recent troubles .

Graff took a seven-day cruise last fall on the Carnival Fantasy to Grand Turk , Half Moon Cay and Nassau , Bahamas and had a wonderful time . `` It was a fantastic trip , '' wrote Graff , a photographer in Fuquay-Varina , North Carolina , in an email .

`` A few veteran cruisers grumbled about the age of the ship , and the decor being dated , but the service and experience was really great , '' he said .

Graff said he would definitely take another Carnival cruise . But he has some conditions .

`` There 's no question that Carnival should be seriously looking into their maintenance policies and double-checking their work to make sure their customers and crews are having the safest voyages possible , '' wrote Graff . `` If these issues continue to go on unchecked , then I 'll change my answer . ''

Carnival cruise line in more troubled waters

Carnival has a window of opportunity to convince customers its ships can sail without too much trouble , according to several travel agents and cruisers interviewed by CNN.com . But the company has to prove it is tackling the recent spate of mechanical issues faced by four Carnival ships , the most serious of which left more than 4,000 people stranded for days aboard the Carnival Triumph last month .

' A grace period ' to fix things

Carnival has a grace period of a couple months to get its act together , according to travel agent Ricci Zukerman . Her mostly high-end clients occasionally book a more budget-oriented Carnival cruise for a family reunion or when they 're bringing teenagers along because `` they 're the fun ships , '' she said .

`` Carnival has been in business for many years , and for a long time there 's never been a hitch , '' said Zukerman , president of Worldview Travel . But they need to attend to their maintenance issues . `` If it happens again , I think people will start worrying . There are other ships in the ocean , '' although none quite so affordable , she said .

Carnival Cruise Lines announced a `` comprehensive review '' this week of all its ships , prompted by the engine fire that led to the Triumph 's stranding in the Gulf of Mexico in February .

As the biggest cruise company in the world , parent company Carnival Corp. has a strong reputation in the industry and among its regular customers , said Kimberly Wilson Wetty , co-president of Valerie Wilson Travel .

In addition to Carnival Cruise Lines , the corporation 's portfolio includes brands such as Holland America Line , Princess Cruises , Seabourn , Cunard and Costa Cruises . The Costa Concordia had a deadly accident off the coast of Italy last year .

Five things we 've learned about cruising

Overall advance bookings are down

Total advance bookings across all of Carnival Corp. 's brands for 2013 are behind 2012 levels , Carnival said in a news release Friday announcing first quarter financial results . But despite the overall lag , booking volume since January for the rest of the year has been `` running significantly higher than last year at slightly higher prices , '' the company said .

`` Despite considerable attention surrounding the Carnival Triumph , we had been encouraged to see booking volumes for Carnival Cruise Lines recover significantly in recent weeks , '' said Micky Arison , chief executive officer of Carnival Corp. .

`` All ships experience some challenges , '' said Wetty , who traditionally books her customers on high-end cruises . `` It 's all the recovery and how they treat the passengers and how they continue to build consumer confidence .

`` For those who are consistent cruisers and know Carnival , I do n't think it 's going to change their buying habits . For new cruisers , it puts a little doubt in their minds . ''

Not every frequent Carnival cruiser is feeling so confident .

`` I have cruised with Carnival on many occasions with my family . They were my -LSB- favorite -RSB- cruise line . That being said , I will stay on land from here on out , '' wrote one CNN.com commenter .

`` Until they have a really really long period of time with no problems I will not consider cruising with them again . This is just way too much . The Concordia going down was bad enough , but all of these are just plain nonsense . It WILL hurt the cruise line . ''

Customers need to be reassured Carnival is doing everything it can to address its ships ' issues , Wetty said .

How Carnival can clean up the PR mess

Customers of canceled cruises complain

Current customers , some of whom have been posting on CNN.com , are having trouble reaching the company in some cases .

`` What about those of us that got our cruise canceled ? '' wrote one commenter , who said she was scheduled to sail on the Carnival Dream . `` I have n't heard anything from Carnival , and I do n't know how long it will take to get a refund . Now we are stuck not knowing what to do for a vacation we saved 8 years to take ! ''

Still , Connie Hammond is one of those Carnival fans who is n't giving up on the cruise line .

`` All three of my prior Carnival cruises were wonderful , food was outstanding , ports were well organized and safe , shipboard activities were plentiful , all for a small budget price , '' Hammond , a resident of Fort Madison , Iowa , wrote in an e-mail .

`` I 'm sure I could have paid $ 1,000 more per person and been impressed much more , but the Carnival cruise was a great vacation and a memorable fun time . ''

Hammond said she expects the recent incidents will be a wake-up call for Carnival 's maintenance program , but she 's not concerned about safety .

She 's already booked her next Carnival cruise , taking her 79-year-old mother and a girlfriend who has never been on a cruise .

After a bad cruise , can you cruise into court ?

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Some previous Carnival passengers say they would cruise with the company again

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Travel agents and passengers say Carnival Cruise Lines needs to examine maintenance issues

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Overall bookings across parent company Carnival Corp. are behind 2012 bookings